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ADIL MUGHAL

I am a theoretical physicist working on the effects of topology and geometry in condensed matter physics. In particular, I am interested in packing problems, foams and the role played by conformal geometries in these systems.


Recent Publications

Demonstration and interpretation of "scutoid" cells in a quasi-2D soap froth

A. Mughal, S.J. Cox, D. Weaire, S.R. Burke, S. HutzlerarXiv:1809.08421 (2018). Submitted to Phil. Mag. Lett.

Recently a novel type of epithelial cell has been discovered and dubbed the "scutoid". It is induced by curvature of the bounding surfaces. We show by simulations and experiments that such cells are to be found in a dry foam subjected to this boundary condition.


SafariScreenSnapz001

                               Scutoid cells in a columnar foam


Theory of rotational columnar structures of soft spheres

J. Winkelmann, A. Mughal, D.B. Williams, D. Weaire, and S. HutzlerarXiv:1808.02952 (2018). Submitted to Phys. Rev. Lett.

There is a growing interest in cylindrical structures of hard and soft particles. A promising new method to assemble such structures has recently been introduced by Lee et al. [T. Lee, K. Gizynski, and B. Grzybowski, Advanced Materials 29, 1704274 (2017)], using rapid rotation around a central axis to drive spheres (which are of lower density than the surrounding fluid) towards the axis, and observing different structures as the number of spheres is varied. Here we present comprehensive analytic energy calculations for such self-assembled structures, based on a generic soft sphere model, from which we obtain a phase diagram. It displays interesting features, including peritectoid points. These analytic calculations are complemented by numerical simulations for finite sample sizes with soft spheres.


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             Phase diagram for soft sphere packings in cylinders


Columnar structures of soft spheres: metastability and hysteresis

A. Mughal, J. Winkelmann, D. Weaire and S. Hutzler, arXiv:1805.07673 (2018). Submitted to Phys. Rev. E.

Previously we reported on the stable (i.e. minimal enthalpy) structures of soft monodisperse spheres in a long cylindrical channel. Here, we present further simulations, which significantly extend the original phase diagram up to D/d = 2.714 (ratio of cylinder and sphere diameters), where the nature of densest sphere packing changes. However, macroscopic systems of this kind are not confined to the ideal equilibrium states of this diagram. Consequently, we explore some of the structural transitions to be expected as experimental conditions are varied; these are in general hysteretic. We represent these transitions in a stability diagram for a representative case. Illustrative videos are included in the supplemental material.


phasediagram

           Phase diagram for soft sphere packings in cylinders


© Adil Mughal 2012 adil.m.mughal@gmail.com